The U.S. Navy is working on new technology for its gas-turbine engines in order to decrease fuel consumption without sacrificing performance.

The answer, according to the Naval Research Laboratory (NRL), is equipping current gas-turbine engines with Rotating Detonation Engine (RDE) technology. These engines could not only efficiently provide propulsion for Navy planes and ships, but also create electricity for an all-electric propulsion system.

The Navy currently uses gas-turbine engines that are based on the Brayton thermodynamic cycle, where air is compressed, combined with fuel, combusted at a constant pressure and expanded. This allows for propulsion or generating electricity, just like the RDEs. However, the Brayton cycle is less efficient than the detonation cycle.

Dr. Kazhikathra Kailasanath, head of NRL's Laboratories for Computational Physics and Fluid Dynamics, noted the following in a 2011 paper for the NRL Review:

The challenge with detonation engines is realizing the efficiency of the detonation cycle. Concepts such as oblique detonation-wave engines have failed to be able to recover the efficiency of this detonation cycle, because much of the energy of the inflow is bound up in kinetic energy, which does not increase the pressure and thus does not improve the efficiency. Pulse detonation engines have taken a different approach by creating an unsteady process that removes the requirement of having high velocity inflow. This creates a whole new set of issues, such as rapid initiation of detonations and the requirement of efficient detonators.

The rotating detonation engine takes a different approach toward realizing the efficiency of the detonation cycle. By allowing the detonation to propagate azimuthally around an annular combustion chamber, the kinetic energy of the inflow can be held to a relatively low value, and thus the RDE can use most of the compression for gains in efficiency, while the flow field matches the steady detonation cycle closely.

Currently, the Navy has 129 ships with 430 gas-turbine engines that burn $2 billion of fuel annually. By equipping engines with RDE technology, power could be increased by 10 percent while fuel consumption would decrease by 25 percent. The Navy could also save $300-$400 million annually.

Not sure if you're actually serious or not, but a gas turbine is cheaper than a nuclear reactor by a factor of several magnitudes. Not to mention running costs, maintenance, fuel and so on.

As for enemy deterrence, water is a fantastic absorber of radiation, you sink a nuclear vessel in the deep ocean and the reactor falls to the bottom where it's a threat to no one except whatever wildlife has the misfortune of happening to exist nearby.

For immediate costs, yes that is true. But you have to maintain oilers to resupply those vessels using gas turbines. Add in the shipboard space required for fuel storage - which could otherwise be used to store weapons or supplies for the crew - and the trade is not necessarily as bad as you think. And from a weapons standpoint, the less frequently you need to resupply a warship, the better off you are.

There is a lot more to it than you think as well. For instance, who would operate these plants? We are already undermanned for the vessels we have today, that is why we offer such high bonuses for nukes to stay in the Navy. I was one of those nukes who served onboard subs, and I refused the 75k bonus to reenlist last year and got out because the job is miserable, mostly due to under manning and the low quality nukes being pumped out of nuke school today to try and fill the gaps.

You also have to realize that with a nuclear plant you require watchstanders to operate it 24/7 (compared to just turning the engine off) and you have to perform an annual test to prove that you can safely and reliably operate the reactor. This test takes a large amount of resources and time as well, leading to more shortfalls in manning and more costs associated with it.

In short, I love nuclear power. It is a safe, reliable, clean energy source (regardless what the jackoffs who have never studied it have told you) that has its uses. It is perfect for submarines and large ships such as carriers, but unless gas prices skyrocket it just doesn't make practical sense to install it onboard everything we have, at least not as long as the public is deathly afraid of things they don't understand.

Lastly, to the OP, please refrain from talking about nuclear power as a deterrent. If a ship using it were hit the reactor would automatically scram and the cooling effect from the ocean would prevent the core from melting down. Even worst case impossible scenario (the enemy sent divers in to manually withdraw the rods somehow to cause a meltdown?) water has a tenth thickness of 24", meaning that every 2 feet of water will reduce radiation by ~90%, so 4 feet away you will have ~1% radiation and so on.

Your obviously an idiot and know nothing about the Navy's nuclear designs of its reactors then. They are not like 3 Mile Island reactors, they are inherently safe. As a Navy Nuke previously myself they are some of the safest reactors that are in operation anywhere. Look at the track record and you will realize that there has never been a meltdown of a single US Navy Reactor.

Really so if the reactor takes a direct hit from a anti ship missile no radiation is going to leak out. You are obviously a retarded ass scratching monkey - since we feel the need to name call over the internet.

You are quite ignorant, aren't you? These reactors are at the very core of each ship protected not only by the external armor of the ship, but also several internal steel walls. The reactor itself is or should be in a protective housing which even if the ship was hit directly on the point closest to the reactor wouldn't blow, and as the previous poster explained a sinking ship would prevent the meltdown. Do you think an oil spill has less ecological impact? Or any of the thousands of contaminants common in any ship and specially in warships? Do you even know what radiation actually is? The problem with nuclear power is mainly the ignorance of the common public and as a consequence the fear of the invisible, unknown and not understood. That's why at a certain age not so long ago common wise women or men were burnt on the stake as witches or hexers. One typical example is protesting the building of an atomic power plant because of the terrible "ghost" of radiation danger and being happy about and supporting coal burning powerplants which actually spew radioactive substances (contained previously in the coal) into the air for everyone to breath (the most dangerous form of radioactive contamination). But coal burning is looked at as something simple and commonplace like the fire you use for cooking or at camping. Something that has been with humanity since its' dawn. I'm surprised each day at the lack of common scientific knowledge and common sense in most people. It's unbelievable how some can be so sure about themselves when their almost complete lack of understanding and ignorance about the world and how it works shows clearly in their eyes.

quote: if the reactor takes a direct hit from a anti ship missile no radiation is going to leak out.

There are so many things wrong with this statement (such as a direct hit, this isn't the deathstar where you can shoot inside a vent to score a direct hit on a reactor). I would be glad to discuss this issue with you in a civilized manner if you at the very least look up the difference between radiation and contamination (and maybe look at the definition of radiation).

I've worked for years in close quarters to a live nuclear reactor while onboard submarines, and I have no problems discussing nuclear power. I will not waste my time with people who are so closed minded that they will not listen to facts and only use keywords and catch phrases they heard from others as arguments (A.K.A. Meltdown, supercritical, Fukushima, etc.)

Why do you think the public is so nervous about nuclear power? Every time they start to become convinced that its safe there is another nuclear accident. Yes before Fukushima people were getting comfortable with the concept of nuclear power again. Pretty sure that was the last straw for most people.

That's the crazy thing. How many died in Fukushima? 2 direct deaths and an estimated 28 (from 3 to 245) indirect ones due to cancer. How many died in the Bangiao Dam accident? 26 thousand! In general hydroelectric power alone has caused about 171 thousand deaths worldwide. Compare that to nuclear. Again fear mongering about the unknown dangers of the invisible radiation is a symptom and example of human stupidity and lack of education rather than a real risk.Look at the following comparisons of death tolls by power generated:http://www.the9billion.com/2011/03/24/death-rate-f...orhttp://www.forbes.com/sites/jamesconca/2012/06/10/...

As you can see the difference is not even in the same order of magnitude with nuclear being the safest power generation technology in history.

My only problem with Nuclear is while I agree the newer power generating reactor designs are great, pebble bed, thorium, traveling wave (if the design finally proves itself), are great. It disappoints me greatly how little progress I see getting the older reactors replaced/upgraded and how little progress I see on research to safely close the fuel cycles for the various designs. (AKA reactors designed to "burn" or reprocess waste into more easily handled products or back into fuel.) I realize some of this is due to limits we put on ourselves in NNPAs since breeders tuned to burn plutonium can just as easly be tuned to make it for example, and lets not forget the joys of running the liquid metalic sodium cooling use in most fast breeders. But this whoe bury it and pretend it all goes away thing is even dumber.

Exactly. Instead of using the newer better and more secure designs and replacing old nuclear power plants with them a lot of ignorant and scientifically illiterate people try to block the construction of new atomic powerplants forcing governments to keep the older less secure designs.

quote: Why do you think the public is so nervous about nuclear power? Every time they start to become convinced that its safe there is another nuclear accident.

The "problem" with nuclear power is that it's an incredibly concentrated power source. A single nuclear reactor replaces about 7 coal plants, or about 5,000-15,000 wind turbines. And a nuclear plant typically has 2-4 reactors.

But when it comes to the consequences of accidents, people think in terms of 1 nuclear reactor = 1 coal plant = 1 wind turbine. Just like people equate 1 airplane crash = 1 car crash and are afraid to fly even though they're more likely to die while riding a car.

If you normalize for the amount of power generated, nuclear turns out to be the safest power source man has ever invented. Yes a single wind turbine is safer than a nuclear reactor. But the 10,000 wind turbines needed to equal the nuclear reactor's power output turn out to be cumulatively more dangerous.

The only other power source which is comparable to nuclear in terms of energy density is hydro. A hydroelectric dam on a large river has a generating capacity similar to or even exceeding a nuclear plant with multiple reactors. This is the reason the worst power generation accident in history (est. 170,000 killed, 6 million buildings destroyed, 11 million people evacuated) was the failure of series of hydroelectric dams. But water is something we deal with every day, while nuclear decay is just an abstract concept. So people fear nuclear while they have no problem with the more dangerous hydro.

Well you can pout and stomp your feet all you want, my side of the argument has won. After Fukushema Nuclear power is basically dead around the world, except in China where they don't care what the public thinks. We were planning on building some new nuclear plants in the US, guess the odds on those being built now.

I suppose it´s not a very nice feeling when other find you ignorant or stupid. You don´t seem a bad person per se, just as previously said ignorant. Yes, there has been some backslash due to the events in Fukushima, but guess what, atomic power plants are still being built and new plants are being planned even now. For example the case of Germany and France. Germany has decided to close their atomic powerplants and import the electricity from other countries, mainly France which has a surplus due to.... "atomic power". : ) : ) In other words, nothing has really changed just that the german people will have negative economic repercussions for this decision, while the french will certainly benefit. Yes, it´s true that for now there is a reduced interest in atomic powerplants, but even so there is a backlog of five to ten years if not more for new reactor housings and such (due to the limited amount of manufacturing capacity).

In short. The common person is pretty ignorant of all scientific matters and very inclined to believe all kinds of missinformation and fearmongering lies. Also that person is also very inclined to fear the unknown. But the truth is that if we allow our decisions to be determined by this common stupidity denominator the countries of the world will suffer the economical and ecological consequences.

Whatever you believe, know this: atomic power is the cleanest and most economically and ecologically sensible energy generation technology humanity has developed till now. If you prefer dying of cancer due to the fumes of coal or oil power plants be my guest. If you think wind and solar power would be enough you have deluded yourself. The inherent instability of such power sources allows it to provide up to 10-15% of the total energy generation capacity. Meaning it´s got its´ place but cannot be the main source of energy for humanity unless you are happy having brownouts all the time or having each family be forced to invest tens of thousands of dollars in battery backups every five years. Not speaking about industry which in some cases MUST have an uninterrupted supply of electricity due to the production processes involved. Fossil fuels (coal, oil or gas) are a very dirty source of energy and one which will get more expensive each day.

There is a lot more information about this subject I could give you. If you are really interested to learn about this, let me know I will gladly help you.

The chances of a direct hit to the reactor of a nuclear vessel such as a Nimitz class carrier is pretty slim. You have the outer armor of the ship as well as the armor around the reactor. Those ships were designed to take 3 times the damage of an Essex-class carrier. Even if the ship is crippled, like most nuclear vessels, the reactor automatically shuts down so the threat of a radiation leak is virtually impossible.

Secondly, isn't most of what you're saying true because of budget cutbacks and the fact that we've severely halted most next-generation power-plant design projects?

It seems to me that if we had kept at it, we would have safer more compact designs today that could be deployed in a wide range of surface ship designs. But I'm just a layman without your real-world experience, of course.

I agree we can't realistically have a 100% nuclear powered surface Navy, but I would think that anything from cruiser-sized on up would benefit greatly from it.

Your welcome, and I highly recommend to everyone to serve at least a 2 year enlistment, even if you are against combat you can always play a support role. It really does make a positive change in most people.

As for designs, we use older designs because they are tried and true. The new Virginia class is a huge step up from the L.A. Class in terms of technology and design, and it can be operated with fewer people. The problem that arises is that the Nuclear Navy can't risk having any type of accident, so we limit pushing new technology until it has been proven and train our crews to handle any (likely and unlikely) scenario.

As for the smaller reactors, I once served onboard the submarine NR-1 (look it up, its a very unique vessel that almost nobody knows about) which had a small, compact reactor and design that could work in any ship. This was made possible by only allowing the most highly qualified nukes to operate it.

To put it simply though, it is possible. We already have usable designs since we have had nuclear cruisers in the past, they were decommissioned though because it was too expensive to run them. We could easily get the costs down if it weren't for public paranoia because we go overboard on making sure nothing happens to any of the reactors. If you could only see the designs we use now they are already extremely safe and only the absolutely worst worst case scenarios could cause any harm, and even then it wouldn't be as bad as people fear.

Unfortunately though people like to live in scared little worlds of their own where they mistakenly believe anything told to them. Instead of trying to understand new technology, they just denounce it as evil (nuclear power) while saying they support non-viable alternatives (wind/solar power) while in reality their own excessive usage of energy forces us to rely on the worst possible alternatives (coal/oil power).

Or here is a crazy concept how about just using standard diesel engines like the commercial shipping industry? If it were more practical to use gas turbines that's what the commercial industry would be using.

Commercial cargo ships have propulsion plants that can efficiently propel them from one cargo port to the next at a modest speed, with a little power diverted to the habitation block for a modest crew.

Military warships have propulsion plants that allow them to maneuver and cruise at considerable speed, while simultaneously providing the energy necessary to support hundreds of crew, radar, weapons, communications, etc. None of this usage is necessary on the practical commercial vessels you compare them with.

Pretty sure you have no idea what your talking about. Thats why the military uses piston engines in planes right? Because they are so powerful? Gas turbines offer far more power for its size, with better reliability.

Gas turbines can power everything, even data centers and when they need it to run 24/7 and not take up a lot of space they go turbine, not diesel.